Semiconductor image pickup device having function circuit block

ABSTRACT

To check circuit characteristics of a function circuit block such as a gain circuit, data indicating an initial set point is set in a data set unit setting time period T 1 . A plurality of electric signals from converting optical signals of pixel cells for an image are accumulated in a pixel array in an accumulating time period T 2 . In a data outputting time period T 3 , a plurality of different set points are set in an automatic set point changing block according to the data set in the data set unit. The electric signals are repeatedly corrected in the gain circuit at a gain while changing the gain corresponding to each of the set points. The corrected electric signals corresponding to the set points are output from a semiconductor image pickup device. In a time period T 4 , the corrected electric signals is calculated, and the gain circuit characteristics are checked.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor image pickup devicesuch as a complementary metal oxide semiconductor (CMOS) image sensor, acharge coupled device (CCD) or a semiconductor device including the CMOSimage sensor or CCD.

2. Description of Related Art

FIG. 7 is a block diagram showing the configuration of a conventionalCMOS image sensor representing a conventional semiconductor image pickupdevice.

In FIG. 7, 1 indicates a conventional CMOS image sensor. 2 indicateseach of a plurality of pixel cells for respectively converting anoptical signal into an electric signal indicating pixel data. 3indicates a pixel array which is composed of the pixel cells 2 arrangedin a two-dimensional array on a chip surface of the CMOS image sensor 1.The optical signals sent from an object, of which an image is picked up,are received in the pixel array 3 and are convened into the electricsignals.

4 indicates a logic input/output terminal for receiving an operationclock signal and data from the outside of the chip and outputting a dataoutput start signal and the like to the outside of the chip. 5 indicatesa data set unit for controlling the CMOS image sensor 31 according tothe data received in the logic input/output terminal 4. 6 indicates aset point register block for registering the data received in the logicinput/output terminal 4, producing a set point for each of a pluralityof function circuit blocks according to the data and supplying the setpoint each function circuit block. 7 indicates a row scanner forselecting a series of pixel cells 2 placed on an arbitrary row of thepixel array 3. 8 indicates a column scanner for selecting a series ofpixel cells 2 placed on an arbitrary column of the pixel array 3.

10 indicates a color tone correcting circuit for correcting a color tone(a red component, a green component and a blue component) of theelectric signals converted in the pixel array 3 according to the setpoint sent from the set point register block 6. 11 indicates a gaincircuit for correcting the electric signals output from the color tonecorrecting circuit 10 at a gain (a ratio of the level of each outputelectric signal to the level of the input electric signal) correspondingto the set point sent from the set point register block 6. 12 indicatesa gamma correcting circuit for correcting the electric signals outputfrom the gain circuit 11 to a degree corresponding to the set point sentfrom the set point register block 6 so as to fit the sensibility of thepixel array 3 to the sensibility of the naked eye. 13 indicates adigital-to-analog (D/A) converter for performing the D/A conversion byusing the set point sent from the set point register block 6 andproducing a reference voltage Vref. 13 a indicates an adder, arranged inthe gamma correcting circuit 12, for adding the reference voltage Vrefproduced in the D/A converter 13 to each electric signal to change thelevel of the electric signal to a level suitable for a circuit connectedto the chip of the CMOS image sensor 1. A group of function circuitblocks 9 is composed of the color tone correcting circuit 10, the gaincircuit 11, the gamma correcting circuit 12 with the adder 13 a and theD/A converter 13.

14 indicates an analog-to-digital (A/D) converter for performing the A/Dconversion for each electric signal corrected in the gamma correctingcircuit 12. 15 indicates an output terminal through which each electricsignal obtained in the A/D converter 14 is output. 16 indicates ananalog pixel output terminal through which each electric signal obtainedin the gamma correcting circuit 12 is output.

Next, an operation of the conventional CMOS image sensor 1 will bedescribed below.

In the check of the function of the conventional CMOS image sensor 1,circuit characteristics of the group of function circuit blocks 9 arechecked. In this check, many set points ranging from several set pointsto tens of set points are sent one after another from the set pointregister block 6 to the group of function circuit blocks 9. Therefore,many gains ranging from one-fold gain to several-fold gain or tens-foldgain are, for example, set in the gain circuit 11.

In a check process of circuit characteristics of a desired functioncircuit block, data indicating a known set point is sent from theoutside of the chip of the conventional CMOS image sensor 1 to the dataset unit 5 through the logic input/output terminal 4, the data isregistered in the set point register block 6, and the known set point issent from the set point register block 6 to the desired function circuitblock. In this case, a prescribed set point has been already sent toeach of the function circuit blocks 9 other than the desired functioncircuit block. Thereafter, a plurality of optical signals input from theimage pickup object to the pixel cells 2 of the pixel array 3 areconverted into a plurality of electric signals, the electric signals arecorrected in the group of function circuit blocks 9 such as the colortone correcting circuit 10, the gain circuit 11, the gamma correctingcircuit 12 with the adder 13 a and the D/A converter 13 according to theknown set point and the prescribed set points to produce a plurality ofcorrected analog electric signals, the corrected analog electric signalsare converted in the A/D converter 14 into a plurality of correcteddigital electric signals, and the corrected digital electric signals areoutput to the outside of the chip of the conventional CMOS image sensor1 through the output terminal 15. Also, the corrected analog electricsignals are output to the outside of the chip of the conventional CMOSimage sensor 1 through the analog pixel output terminal 16.

Thereafter, circuit characteristics of the desired function circuitblock are checked according to the optical signals input to the pixelarray 3, the corrected analog or digital electric signals and the knownset point supplied to the desired function circuit block in the outsideof the chip of the conventional CMOS image sensor 1. Therefore, in caseswhere a plurality of known set points different from each other are sentto the desired function circuit block, circuit characteristics of thedesired function circuit block can be precisely checked.

FIG. 8 is an explanatory view of a check sequence of circuitcharacteristics of a desired function circuit block performed in theconventional CMOS image sensor 1.

As shown in FIG. 8, a first set point is set in the data set unit 5 andis sent to a desired function circuit block in a data set unit settingtime period T1. In this case, a prescribed set point has been alreadysent to each of the function circuit blocks 9 other than the desiredfunction circuit block. Thereafter, when electric signals are preparedin the pixel array 3 during an accumulating time period (or a standbytime period) T2, the data outputting is started in the pixel array 3. Indetail, in a data outputting time period (or an image pickup timeperiod, for example, corresponding to one frame) T3, all the electricsignals are sent from the pixel cells 2 of the pixel array 3 to thegroup of function circuit blocks 9, and corrected electric signals areoutput from the group of function circuit blocks 9 to the outside of theconventional CMOS image sensor 1. For example, one electric signal D isacquired in the group of function circuit blocks 9 and is output to theoutside in a part of the data outputting time period T3. Thereafter, ina calculating and judging time period T4, the calculation for theelectric signals and the judgment (or check) of circuit characteristicsof the desired function circuit block are performed in the outside ofthe conventional CMOS image sensor 1.

Therefore, in this check sequence, in cases where circuitcharacteristics of the desired function circuit block are checked bysending M set points (first set point, second set point,--, and M-th setpoint) different from each other to the desired function circuit blockone after another, it is required that a series of time periods T1 to T4is repeated M times.

Because the conventional CMOS image sensor 1 representing theconventional semiconductor image pickup device has the above-describedconfiguration, a problem has arisen that a series of time periods T1 toT4 is required for each set point to check circuit characteristics ofthe desired function circuit block according to many set points.

Also, a problem has arisen that it takes a lot of time to check circuitcharacteristics of the group of function circuit blocks 9 in theconventional CMOS image sensor 1.

SUMMARY OF THE INVENTION

An object of the present invention is to provide, with due considerationto the drawbacks of the conventional semiconductor image pickup device,a semiconductor image pickup device in which a series of time periodsrequired to check circuit characteristics of a function circuit block ora plurality of function circuit blocks is shortened.

The object is achieved by the provision of a semiconductor image pickupdevice comprising a pixel array for converting an optical signal of animage input into an electric signal to pickup the image, an automaticset point changing block for producing a plurality of set pointsdifferent from each other according to data input from an outside in animage pickup time period of the pixel array, and a function circuitblock for correcting the electric signal obtained in the pixel arrayaccording to each of the set points produced in the automatic set pointchanging block in the image pickup time period of the pixel array andoutputting the corrected electric signals corresponding to the setpoints to the outside.

In the above configuration, circuit characteristics of the functioncircuit block are checked in the outside of the semiconductor imagepickup device according to the optical signal input to the pixel array,the corrected electric signals output from the function circuit blockand the set points produced in the automatic set point changing block.Accordingly, because the set points different from each other areproduced in the automatic set point changing block in the image pickuptime period of the pixel array, the corrected electric signalscorresponding to the plurality of set points can be output by preparingthe electric signal only once, and a series of time periods required tocheck circuit characteristics of the function circuit block can beshortened.

It is preferred that the automatic set point changing block comprises anincrement function register for producing the set points by incrementinga set point by a prescribed value in the image pickup time period of thepixel array. Therefore, a current set point obtained by adding theprescribed value to a preceding set point can be repeatedly sent to thefunction circuit block.

It is preferred that the automatic set point changing block comprises adecrement function register for producing the set points by decrementinga set point by a prescribed value in the image pickup time period of thepixel array. Therefore, a current set point obtained by subtracting theprescribed value from a preceding set point can be repeatedly sent tothe function circuit block.

Also, it is preferred that the automatic set point changing blockcomprises a shift function register for producing the set points byrepeatedly doubling or halving a set point in the image pickup timeperiod of the pixel array. Therefore, a current set point obtained bydoubling or halving a preceding set point can be repeatedly sent to thefunction circuit block.

Also, it is preferred that the automatic set point changing blockcomprises a plurality of set point registers for registering the setpoints so as to be read out in the image pickup time period of the pixelarray. Therefore, a plurality of arbitrary set points different fromeach other can be sent to the function circuit block.

Also, it is preferred that the automatic set point changing blockcomprises a memory for storing the set points so as to be read out inthe image pickup time period of the pixel array. Therefore, a pluralityof arbitrary set points different from each other can be sent to thefunction circuit block.

The object is also achieved by the provision of a semiconductor imagepickup device comprising a pixel array for converting an optical signalof an image input into an electric signal to pickup the image, aplurality of automatic set point changing blocks for respectivelyproducing a plurality of set points different from each other accordingto data input from an outside in an image pickup time period of thepixel array, and a plurality of function circuit blocks, correspondingto the automatic set point changing blocks respectively, forrespectively receiving each of the set points from the correspondingautomatic set point changing block at a timing different from those inthe other function circuit blocks, respectively correcting the electricsignal obtained in the pixel array according to each of the set pointsat the corresponding timing in the image pickup time period of the pixelarray, and outputting the corrected electric signals corresponding tothe set points to the outside.

In the above configuration, the timing of the correction of the electricsignal in one function circuit block based on each set point differsfrom those in the function circuit blocks, and circuit characteristicsof the function circuit blocks are checked in the outside of thesemiconductor image pickup device according to the optical signal inputto the pixel array, the corrected electric signals output from thefunction circuit blocks and the set points produced in the automatic setpoint changing block. Accordingly, because the set points different fromeach other are produced in each automatic set point changing block inthe image pickup time period of the pixel array, the corrected electricsignals corresponding to the plurality of set points produced in theautomatic set point changing blocks can be output by preparing theelectric signal only once, circuit characteristics of the functioncircuit blocks can be minutely checked, and a series of time periodsrequired to check circuit characteristics of the function circuit blockscan be shortened.

It is preferred that each automatic set point changing block comprisesan increment function register for producing the set points byincrementing a set point by a prescribed value in the image pickup timeperiod of the pixel array. Therefore, a current set point obtained byadding the prescribed value to a preceding set point can be repeatedlysent to each function circuit block.

Also, it is preferred that each automatic set point changing blockcomprises a decrement function register for producing the set points bydecrementing a set point by a prescribed value in the image pickup timeperiod of the pixel array. Therefore, a current set point obtained bysubtracting the prescribed value from a preceding set point can berepeatedly sent to each function circuit block.

Also, it is preferred that each automatic set point changing blockcomprises a shift function register for producing the set points byrepeatedly doubling or halving a set point in the image pickup timeperiod of the pixel array. Therefore, a current set point obtained bydoubling or halving a preceding set point can be repeatedly sent to eachfunction circuit block.

Also, it is preferred that each automatic set point changing blockcomprises a plurality of set point registers for registering the setpoints so as to be read out in the image pickup time period of the pixelarray. Therefore, a plurality of arbitrary set points different fromeach other can be sent to each function circuit block.

Also, it is preferred that each automatic set point changing blockcomprises a memory for storing the set points so as to be read out inthe image pickup time period of the pixel array. Therefore, a pluralityof arbitrary set points different from each other can be sent to eachfunction circuit block.

It is preferred that each automatic set point changing block comprisesan automatic setting unit which produces the set points optimum to checkthe corresponding function circuit block. Therefore, the configurationof each automatic set point changing block can be simplified, and anarea of a chip of the semiconductor image pickup device can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of a CMOS imagesensor representing a semiconductor image pickup device according to afirst embodiment of the present invention;

FIG. 2 shows a check sequence of circuit characteristics of one functioncircuit block according to the first embodiment of the presentinvention;

FIG. 3 is a block diagram showing the configuration of a CMOS imagesensor representing a semiconductor image pickup device according to asecond embodiment of the present invention;

FIG. 4 shows a check sequence of circuit characteristics of both a gaincircuit and a gamma correcting circuit according to the secondembodiment of the present invention;

FIG. 5 is a block diagram showing the configuration of a CMOS imagesensor representing a semiconductor image pickup device according to athird embodiment of the present invention;

FIG. 6 is a block diagram showing the configuration of a CMOS imagesensor representing a semiconductor image pickup device according to afourth embodiment of the present invention;

FIG. 7 is a block diagram showing the configuration of a conventionalCMOS image sensor representing a conventional semiconductor image pickupdevice; and

FIG. 8 is an explanatory view of a check sequence of circuitcharacteristics of a function circuit block performed in theconventional CMOS image sensor shown in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described withreference to the accompanying drawings.

Embodiment 1

FIG. 1 is a block diagram showing the configuration of a CMOS imagesensor representing a semiconductor image pickup device according to afirst embodiment of the present invention.

In FIG. 1, 31 indicates a CMOS image sensor. 2 indicates each of aplurality of pixel cells for receiving a plurality of optical signalsfrom an image pickup object and converting the optical signals into aplurality of electric signals indicating pieces of pixel data. 3indicates a pixel array which is composed of the pixel cells 2 arrangedin a two-dimensional array on a chip surface of the CMOS image sensor31. An end-of-row signal is generated in the pixel array 3 each timepixel data of a pixel placed at the end of a row is output from thepixel array 3.

4 indicates a logic input/output terminal for receiving an operationclock signal and data from the outside of the chip and outputting a dataoutput start signal and the like to the outside of the chip. 5 indicatesa data set unit for controlling the CMOS image sensor 31 according tothe data received in the logic input/output terminal 4. 6 indicates aset point register block for registering the data received in the logicinput/output terminal 4, controlling an automatic set point changingblock and a plurality of multiplexers and supplying a prescribed setpoint to a group of function circuit blocks. 7 indicates a row scannerfor selecting a series of pixel cells 2 of an arbitrary row placed onthe pixel array 3. 8 indicates a column scanner for selecting a seriesof pixel cells 2 of an arbitrary column placed on the pixel array 3.

17 indicates an automatic set point changing block for outputting aplurality of set points different from each other in an image pickuptime period, for example, corresponding to one frame. 22 indicates adata line connecting the data set unit 5 and the automatic set pointchanging block 17. 23 indicates an end-of-row signal line through whichthe end-of-row signal generated in the pixel array 3 is transmitted tothe automatic set point changing block 17.

In the automatic set point changing block 17, 18 indicates an incrementfunction register for incrementing a preceding set point by a prescribedvalue (for example, “1”) in response to each end-of-row signal to obtaina current set point and outputting the current set point. 19 indicates adecrement function register for decrementing a preceding set point by aprescribed value (for example, “1”) in response to each end-of-rowsignal to obtain a current set point and outputting the current setpoint. 20 indicates a shift function register for doubling a precedingset point in response to each end-of-row signal to obtain a current setpoint and outputting the current set point. 21 indicates a multiplexerfor selecting one of the current set points output from the incrementfunction register 18, the decrement function register 19 and the shiftfunction register 20.

24 indicates each of a plurality of multiplexers (a selecting portion)for respectively selecting either the prescribed set point output fromthe set point register block 6 or the current set point output from theautomatic set point changing block 17. 10 indicates a color tonecorrecting circuit for correcting a color tone (a red component, a greencomponent and a blue component) of each electric signal converted in thepixel array 3 according to each set point selected in the correspondingmultiplexer 24. 11 indicates a gain circuit for correcting the electricsignals sent from the color tone correcting circuit 10 at a gain (aratio of the level of each output electric signal to the level of theinput electric signal) which corresponds to each set point selected inthe corresponding multiplexer 24. 12 indicates a gamma correctingcircuit for correcting the electric signals output from the gain circuit11 to a degree corresponding to each set point selected in thecorresponding multiplexer 24 so as to fit the sensibility of the pixelarray 3 to the sensibility of the naked eye. 13 indicates a D/Aconverter for performing the D/A conversion for each set point selectedin the corresponding multiplexer 24 to produce a reference voltage Vref.13 a indicates an adder, arranged in the gamma correcting circuit 12,for adding the reference voltage Vref produced in the D/A converter 13to the electric signal to change the level of the electric signal to alevel suitable for a circuit connected to the chip of the CMOS imagesensor 31. A group of function circuit blocks 9 is composed of the colortone correcting circuit 10. the gain circuit 11, the gamma correctingcircuit 12 with the adder 13 a and the D/A converter 13.

14 indicates an A/D converter for performing the A/D conversion for eachelectric signal corrected in the gamma correcting circuit 12. 15indicates an output terminal through which each electric signal obtainedin the A/D converter 14 is output. 16 indicates an analog pixel outputterminal through which each electric signal obtained in the gammacorrecting circuit 12 is output.

Next, an operation of the CMOS image sensor 31 will be described below.

To examine the function of the CMOS image sensor 31 in the manufacturingof the CMOS image sensor 31, circuit characteristics of the group offunction circuit blocks 9 composed of the color tone correcting circuit10, the gain circuit 11, the gamma correcting circuit 12 with the adder13 a and the D/A converter 13 are checked.

FIG. 2 shows a check sequence of circuit characteristics of one functioncircuit block according to the first embodiment of the presentinvention.

In the check of circuit characteristics of the group of function circuitblocks 9, the check of circuit characteristics of the gain circuit 11 isdescribed as a representative example. In this case, data (control data)indicating an initial set point, a prescribed set point, the selectionin the automatic set point changing block 17 and the selection in themultiplexers 24 is supplied from the outside of the chip of the CMOSimage sensor 31 to the data set unit 5 through the logic input/outputterminal 4, and the data is registered in the set point register block6. The data is sent to the automatic set point changing block 17 throughthe data line 22, and the automatic set point changing block 17 iscontrolled according to the data. In cases where the increment functionregister 18 is selected according to the data, a set point output fromthe increment function register 18 is selected in the multiplexer 21. Anoutput of the increment function register 18 is preset to the initialset point of “1”. Also, the multiplexers 24 are controlled according tothe data (control data) registered in the set point register block 6. Inthis case, a current set point output from the automatic set pointchanging block 17 is selected in only the multiplexer 24 connected tothe gain circuit 11, and a prescribed set point (for example, set to“1”) output from the set point register block 6 is selected in themultiplexers 24 connected to the color tone correcting circuit 10, thegamma correcting circuit 12 and the D/A converter 13 respectively. Thesetting of the data to the data set unit 5 and the selection of thecurrent set point or the prescribed set point in the group of functioncircuit blocks 9 are performed in a data set unit setting time periodT1.

Thereafter, a plurality of electric signals (or pieces of pixel data)obtained from a plurality of optical signals input to the pixel cells 2are accumulated in the pixel array 3 in an accumulating time period T2,and the electric signals of all the pixel cells 2 of the pixel array 3are output to the outside of the chip of the CMOS image sensor 31through the group of function circuit blocks 9, the output terminal 15and the analog pixel output terminal 16 in a data outputting time periodT3. During the data outputting time period T3, the electric signals arecorrected according to the current set point and the prescribed setpoint in the color tone correcting circuit 10, the gain circuit 11, thegamma correcting circuit 12 with the adder 13 a and the D/A converter13, and the corrected electric signals are converted into digitalsignals in the A/D converter 14.

Here, when a plurality of electric signals of a first row are outputfrom the pixel array 3 to the group of function circuit blocks 9 in afirst part of the data outputting time period T3, the initial set pointof “1” set in the increment function register 18 is sent to the gaincircuit 11 through the multiplexer 21 and the multiplexer 24 connectedto the gain circuit 11, and the gain is set to one-fold gain in the gaincircuit 11. Also, the prescribed set point (for example, set to “1”) ofthe set point register block 6 is sent to the color tone correctingcircuit 10, the gamma correcting circuit 12 and the D/A converter 13.Thereafter, the electric signals corrected in the group of functioncircuit blocks 9 are output from the CMOS image sensor 31 as pieces ofpixel data D1.

Also, an end-of-row signal is output from the pixel array 3 to theautomatic set point changing block 17 through the end-of-row signal 23when the outputting of the electric signals of the current row iscompleted. In the automatic set point changing block 17, the precedingset point of the increment function register 18 is incremented inresponse to the end-of-row signal to produce a current set point set to“2”, and this current set point is sent to the gain circuit 11.Therefore, in a second part of the data outputting time period T3, thegain is set to twofold gain in the gain circuit 11, a plurality ofelectric signals of a second row output from the pixel array 3 arecorrected in the gain circuit 11 at twofold gain and are corrected inthe color tone correcting circuit 10, the gamma correcting circuit 12with the adder 13 a and the D/A converter 13 by using the prescribed setpoint, and the corrected electric signals are output from the CMOS imagesensor 31 as pieces of pixel data D2. In this case, the prescribed setpoint sent to the color tone correcting circuit 10, the gamma correctingcircuit 12 and the D/A converter 13 is fixed.

As is described above, in the data outputting time period T3, the setpoint registered in the increment function register 18 is incrementedeach time the electric signals of one row are output from the pixelarray 3, the gain set in the gain circuit 11 is increased from one-foldgain to the M-fold gain, the electric signals of each row are correctedin the group of function circuit blocks 9 including the gain circuit 11in which the gain is increased, and pieces of pixel data D1, D2,--,D_(M) produced from the optical signals of the M rows of the pixel array3 are output from the CMOS image sensor 31 to the outside. Thereafter,the calculation for the pieces of pixel data D1, D2,--, D_(M) and thejudgment (or check) for circuit characteristics of the gain circuit 11are performed in the outside of the CMOS image sensor 31 in acalculating and judging time period T4. That is to say, circuitcharacteristics of the gain circuit 11 for the set points are checkedaccording to the optical signals input to the pixel array 3, theelectric signals output from the group of function circuit blocks 9 andthe set points supplied from the outside to the group of functioncircuit blocks 9.

In the first embodiment, the increment function register 18 is selectedby the multiplexer 21. However, it is applicable that the decrementfunction register 19 or the shift function register 20 be selected bythe multiplexer 21 in place of the increment function register 18. Inthe decrement function register 19, an arbitrary value is preset as aninitial value, a current set point is obtained by decrementing theinitial value by a prescribed value each time the end-of-row signal isreceived, and the current set point is output.

In the shift function register 20, the least significant bit (LSB) ispreset to “1”, and the other bits are preset to “0”. Each time theend-of-row signal is received, the shift operation to the left isperformed while setting “0” to the LSB. That is to say, the set point isdoubled each time the end-of-row signal is received. Therefore, becausethe gain set in the gain circuit 11 is changed in the order of one-foldgain, twofold gain, fourfold gain, eightfold gain,--, 2^((M−1))-foldgain in that order, the shift function register 20 is effective to checkcircuit characteristics of the gain circuit 11. Also, in the shiftfunction register 20, as another shift method, the most significant bit(MSB) is preset to “1”, and the other bits are preset to “0”. Each timethe end-of-row signal is received, the shift operation to the right isperformed while setting “0” to the MSB. That is to say, the set point ishalved each time the end-of-row signal is received. Therefore, becausethe gain set in the gain circuit 11 is changed in the order of2^((M−1))-fold gain,--, eightfold gain, fourfold gain, twofold gain andone-fold gain in that order.

Also, in the first embodiment, the increment in the increment functionregister 18 is performed each time the electric signals of one row areoutput to the group of function circuit block 9. However, it isapplicable that the increment in the increment function register 18 beperformed every plurality of rows or every several pixels, of which thenumber is arbitrary, by using a calculating unit or an operation clocksignal.

Also, in the first embodiment, the current set point of the automaticset point changing block 17 is sent to only the gain circuit 11.However, it is applicable that the current set point of the automaticset point changing block 17 be sent to the color tone correcting circuit10, the gamma correcting circuit 12 and/or the D/A converter 13 in placeof (or in addition to) the gain circuit 11. In this case, circuitcharacteristics of the color tone correcting circuit 10, the gammacorrecting circuit 12 and/or the D/A converter 13 can be checked inplace of (or in addition to) circuit characteristics of the gain circuit11.

Also, in the first embodiment, the prescribed set point set to “1” issupplied from the set point register block 6 to the color tonecorrecting circuit 10, the gamma correcting circuit 12 and/or the D/Aconverter 13. However, it is applicable that the prescribed set point ofthe set point register block 6 be preset to an arbitrary value.

Accordingly, in the first embodiment, because a plurality of set pointsdifferent from each other can be sent from the automatic set pointchanging block 17 to one function circuit block (or a plurality offunction circuit blocks) in the data outputting time period T3 (or oneimage pickup time period of the pixel array 3, for example,corresponding to one frame), all the electric signals accumulated in thepixel array 3 can be corrected in the group of function circuit blocks 9and are output to the outside of the CMOS image sensor 31 in the dataoutputting time period T3, and a series of time periods required tocheck circuit characteristics of the function circuit block (or theplurality of function circuit blocks 9) can be shortened.

Embodiment 2

FIG. 3 is a block diagram showing the configuration of a CMOS imagesensor representing a semiconductor image pickup device according to asecond embodiment of the present invention. The constituent elements,which are the same as those shown in FIG. 1, are indicated by the samereference numerals as those of the constituent elements shown in FIG. 1,and additional description of those constituent elements is omitted.

In a second embodiment, as shown in FIG. 3, the automatic set pointchanging block 17 connected to the color tone correcting circuit 10through one multiplier 24, the automatic set point changing block 17connected to the gain circuit 11 through one multiplier 24, theautomatic set point changing block 17 connected to the gamma correctingcircuit 12 through one multiplier 24 and the automatic set pointchanging block 17 connected to the D/A converter 13 through onemultiplier 24 are arranged in the CMOS image sensor 31.

FIG. 4 shows a check sequence of circuit characteristics of both thegain circuit 11 and the gamma correcting circuit 12 according to thesecond embodiment of the present invention.

Next, an operation of the CMOS image sensor 31 different from that inthe first embodiment will be described below. The check of circuitcharacteristics of both the gain circuit 11 and the gamma correctingcircuit 12 is described as a representative example. In this case, dataindicating an initial set point of each automatic set point changingblock 17 and a prescribed set point is supplied from the outside of thechip of the CMOS image sensor 31 to the data set unit 5 through thelogic input/output terminal 4, the data is registered in the set pointregister block 6, and the data indicating the initial set point is sentto each automatic set point changing block 17 through the data line 22.Also, a set point output from the automatic set point changing block 17corresponding to the gain circuit 11 is selected in the multiplexer 24connected to the gain circuit 11, a set point output from the automaticset point changing block 17 corresponding to the gamma correctingcircuit 12 is selected in the multiplexer 24 connected to the gammacorrecting circuit 12, and the prescribed set point output from the setpoint register block 6 is selected in the other multiplexers 24connected to the color tone correcting circuit 10 and the D/A converter13 respectively. The setting of the data to the data set unit 5 and theselection of the current set point or the prescribed set point in themultipliers 24 are performed in a data set unit setting time period T1.

Thereafter, a plurality of electric signals (or pieces of pixel data)obtained from a plurality of optical signals input to the pixel cells 2are accumulated in the pixel array 3 in an accumulating time period T2in the same manner as in the first embodiment.

In cases where the shift function register 20 is selected in each of theautomatic set point changing blocks 17 corresponding to the gain circuit11 and the gamma correcting circuit 12 respectively, set points set to“2^(i)” (i=0 to M) are sent to the gain circuit 11 one after another,and set points set to “2^(j)” (j=0 to N) are sent to the gammacorrecting circuit 12 one after another.

In detail, in a gamma correction first data outputting time period T3−1of a data outputting time period T3, an initial set point of “2⁰” outputfrom the automatic set point changing block 17 corresponding to thegamma correcting circuit 12 is sent to the gamma correcting circuit 12to check circuit characteristics of the gamma correcting circuit 12, thegain in the gain circuit 11 is changed in the order of one-fold gain,twofold gain,--, and 2^(M)-fold gain in the same manner as in the firstembodiment to check circuit characteristics of the gain circuit 11 byusing the electric signals output from the pixel cells 2 of the firstrow, the second row,--, and the 2^((M+1))-th row, and pieces of pixeldata D1, D2,--, D2 ^(M) corresponding to the first set point set in thegamma correcting circuit 12 are output from the CMOS image sensor 31 tothe outside.

Thereafter, the set point output from the automatic set point changingblock 17 to the gamma correcting circuit 12 is changed each time theend-of-row signal indicating the end of the final row (in this example,the (M+1)-th row) is received in the automatic set point changing block17 corresponding to the gamma correcting circuit 12. In other words, theset point is changed each time the gain change in the order of one-foldgain, twofold gain,--, and 2^(M)-fold gain is completed in the gaincircuit 11. Therefore, in a gamma correction second data outputting timeperiod T3−2 of the data outputting time period T3, a second set point of“2¹” output from the automatic set point changing block 17 correspondingto the gamma correcting circuit 12 is sent to the gamma correctingcircuit 12 to check circuit characteristics of the gamma correctingcircuit 12, the gain in the gain circuit 11 is changed in the order ofone-fold gain, twofold gain,--, and 2^(M)-fold gain to check circuitcharacteristics of the gain circuit 11 by using the electric signalsagain output from the pixel cells 2 of the first row, the second row,--,and the 2^((M+1))-th row, and pieces of pixel data D1, D2,--, D2 ^(M)corresponding to the second set point set in the gamma correctingcircuit 12 are output from the CMOS image sensor 31 to the outside.

Finally, in a gamma correction 2^(N)-th data outputting time periodT3-2^(N) of the data outputting time period T3, a final set point of“2^(N)” output from the automatic set point changing block 17corresponding to the gamma correcting circuit 12 is sent to the gammacorrecting circuit 12 to check circuit characteristics of the gammacorrecting circuit 12, the gain in the gain circuit 11 is changed in theorder of one-fold gain, twofold gain,--, and 2^(M)-fold gain to checkcircuit characteristics of the gain circuit 11 by using the electricsignals again output from the pixel cells 2 of the first row, the secondrow,--, and the 2^((M+1))-th row, and pieces of pixel data D1, D2,--, D2^(M) corresponding to the final set point set in the gamma correctingcircuit 12 are output from the CMOS image sensor 31 to the outside.

Thereafter, in a calculating and judging time period T4, the calculationfor the pieces of pixel data D1, D2,--, D2 ^(M) corresponding to thefirst to final set points set in the gamma correcting circuit 12 isperformed in the outside of the CMOS image sensor 31, and the judgment(or check) for circuit characteristics of both the gain circuit 11 andthe gamma correcting circuit 12 is performed in the outside of the CMOSimage sensor 31.

As is described above, in the second embodiment, a timing of thecorrection of the electric signals base on each set point in onefunction circuit block such as the gain circuit 11 differs from a timingof the correction of the electric signals in another function circuitblock such as the gamma correcting circuit 12. For example, a set pointsent to the gamma correcting circuit 12 is changed each time all setpoints are sent to the gain circuit 11, and all set points are finallysent to the gamma correcting circuit 12 in the data outputting timeperiod T3 (or one image pickup time period of the pixel array 3, forexample, corresponding to one frame). Accordingly, circuitcharacteristics of a plurality of function circuit blocks can beminutely checked.

Also, it is not required to again accumulate all the electric signalseach time a set point sent to the gamma correcting circuit 12 ischanged. Therefore, one data set unit setting time period T1 and oneaccumulating time T2 are only required to check circuit characteristicsof a plurality of function circuit blocks. Accordingly, a plurality ofset points different from each other can be sent from the automatic setpoint changing block 17 to each of a plurality of function circuits inthe data outputting time period T3 (or one image pickup time period ofthe pixel array 3, for example, corresponding to one frame), and aseries of time periods required to check circuit characteristics of thefunction circuit blocks can be shortened.

Embodiment 3

FIG. 5 is a block diagram showing the configuration of a CMOS imagesensor representing a semiconductor image pickup device according to athird embodiment of the present invention. The constituent elements,which are the same as those shown in FIG. 3, are indicated by the samereference numerals as those of the constituent elements shown in FIG. 3,and additional description of those constituent elements is omitted.

In a third embodiment, as shown in FIG. 5, an automatic set pointchanging block 17 a corresponding to the gain circuit 11 and anautomatic set point changing block 17 b corresponding to the gammacorrecting circuit 12 are arranged in the CMOS image sensor 31. Theautomatic set point changing block 17 a has the increment functionregister 18 and the shift function register 20. The automatic set pointchanging block 17 b has only the shift function register 20.

Next, an operation of the CMOS image sensor 31 different from that inthe second embodiment will be described below.

Though the automatic set point changing blocks 17 corresponding to thegroup of function circuit blocks 9 are arranged in the secondembodiment, an automatic set point changing block having a type ofautomatic setting register (or types of automatic setting registers)optimum to each function circuit block is arranged for the functioncircuit block. In detail, because a series of set points produced ineither the increment function register 18 or the shift function register20 are optimum to check circuit characteristics of the gain circuit 11,in cases where circuit characteristics of the gain circuit 11 arechecked, a series of set points produced in the automatic set pointchanging block 17 a are sent to the gain circuit 11. Also, because aseries of set points produced in the shift function register 20 areoptimum to check circuit characteristics of the gamma correcting circuit12, in cases where circuit characteristics of the gamma correctingcircuit 12 are checked, a series of set points produced in the automaticset point changing block 17 b are sent to the gain circuit 11.

Accordingly, in the third embodiment, because the automatic set pointchanging block is optimized for each function circuit block, theautomatic set point changing block corresponding to each functioncircuit block can be simplified, and an area occupied by the chip of theCMOS image sensor 31 can be reduced.

Embodiment 4

FIG. 6 is a block diagram showing the configuration of a CMOS imagesensor representing a semiconductor image pickup device according to afourth embodiment of the present invention. The constituent elements,which are the same as those shown in FIG. 1, are indicated by the samereference numerals as those of the constituent elements shown in FIG. 1,and additional description of those constituent elements is omitted.

In a fourth embodiment, as shown in FIG. 6, a series of set pointsproduced in an automatic set point changing block 17 c are sent to thecolor tone correcting circuit 10, the gain circuit 11, the gammacorrecting circuit 12 and/or the D/A converter 13 through themultiplexer 24. The automatic set point changing block 17 c has a firstset point register 25, a second set point register 25,--, an (M−1)-thset point register 25 and an M-th set point register 25.

Next, an operation of the CMOS image sensor 31 different from that inthe first embodiment will be described below.

Data indicating a plurality of arbitrary set points different from eachother and a prescribed set point (for example, set to “1”) is registeredin the set point register block 6. The number of arbitrary set points isM. The data is sent to the automatic set point changing block 17 cthrough the data line 22, and the arbitrary set points are set in theset point registers 25 respectively. Thereafter, circuit characteristicsof the gain circuit 11 are checked as a representative example.

In detail, a set point output from the automatic set point changingblock 17 c is selected in only the multiplexer 24 connected to the gaincircuit 11, and the prescribed set point output from the set pointregister block 6 is selected in the multiplexers 24 connected to thecolor tone correcting circuit 10, the gamma correcting circuit 12 andthe D/A converter 13 respectively. Thereafter, the set point registeredin the first set point register 25 of the automatic set point changingblock 17 c is sent to the gain circuit 11 as an initial set point tocheck circuit characteristics of the gain circuit 11. Thereafter, theselection of the set point register 25 performed in the multiplexer 21of the automatic set point changing block 17 c is changed each time theend-of-row signal produced in the pixel array 3 is received in theautomatic set point changing block 17 c. Therefore, the set pointregistered in the second set point register 25,--, the set pointregistered in the (M-1)-th set point register 25 and the set pointregistered in the M-th set point register 25 are sent to the gaincircuit 11 in that order to check circuit characteristics of the gaincircuit 11.

In the fourth embodiment, the arbitrary set points different from eachother are set in the set point registers 25 of the automatic set pointchanging block, 17 c respectively. However, it is applicable that amemory be arranged in place of the automatic set point changing block 17c. In this case, a plurality of arbitrary set points different from eachother are stored in the memory through the logic input/output terminal4, the data set unit 5 and the data line 22, the set point read out fromthe memory is changed each time the end-of-row signal produced in thepixel array 3 is output, and the set points read out from the memory aresent to the gain circuit 11 in a prescribed order.

Also, it is applicable that the automatic set point changing block 17 cor a memory be arranged in the CMOS image sensor 31 in place of eachautomatic set point changing block 17 in the second or third embodiment.

As is described above, in the fourth embodiment, circuit characteristicsof each function circuit block can be checked during the data outputtingtime period T3 by using a series of arbitrary set points received in thefunction circuit block in the prescribed order, and a series of timeperiods required to check circuit characteristics of a function circuitblock or a plurality of function circuit blocks can be shortened.

What is claimed is:
 1. A semiconductor image pickup device having afunction to check a function circuit block, comprising a pixel array: apixel array for converting an optical signal of an image input into anelectric signal to pickup the image; an automatic set point changingblock for producing a plurality of set points, which are different fromeach other, according to data input from outside the semiconductor imagepickup device in an image pickup time period of the pixel arraycorresponding to one frame; and the function circuit block forcorrecting the electric signal obtained in the pixel array according toeach of the set points in the image pickup time period of the pixelarray, corresponding to one frame and for outputting the correctedelectric signals, corresponding to the set points, to the outside; a setpoint register block for supplying a set point and control data to thefunction circuit block; and a selecting portion for selecting therespective set points of the function circuit block from the set pointregister block or the automatic set point changing block according tothe control data from the set point register block.
 2. A semiconductorimage pickup device according to claim 1, wherein the automatic setpoint changing block comprises an increment function register forproducing the set points by incrementing a set point by a prescribedvalue in the image pickup time period of the pixel array.
 3. Asemiconductor image pickup device according to claim 1, wherein theautomatic set point changing block comprises a decrement functionregister for producing the set points by decrementing a set point by aprescribed value in the image pickup time period of the pixel array. 4.A semiconductor image pickup device according to claim 1, wherein theautomatic set point changing block comprises a shift function registerfor producing the set points by repeatedly doubling or halving a setpoint in the image pickup time period of the pixel array.
 5. Asemiconductor image pickup device according to claim 1, wherein theautomatic set point changing block comprises a plurality of set pointregisters for registering the set points so as to be read out in theimage pickup time period of the pixel array.
 6. A semiconductor imagepickup device according to claim 1, wherein the automatic set pointchanging block comprises a memory for storing the set points so as to beread out in the image pickup time period of the pixel array.
 7. Asemiconductor image pickup device having a function to check a pluralityof function circuit blocks, comprising: a pixel array for converting anoptical signal of an image input into an electric signal to pickup theimage; a plurality of automatic set point changing blocks forrespectively producing a plurality of set points, which are differentfrom each other, according to data input from outside the semiconductorimage pickup device in an image pickup time period of the pixel arraycorresponding to one frame; the plurality of function circuit blocks,each corresponding to one of the automatic set point changing blocks,each function circuit block for respectively receiving each of the setpoints, at a timing which is different from timing in the other functioncircuit blocks, for correcting the electric signal obtained in the pixelarray according to each of the set points at the corresponding timing inthe image pickup time period of the pixel array corresponding to oneframe, and for outputting the corrected electric signals, correspondingto the set points, to the outside; a set point register block forsupplying a set point and control data to the function circuit block;and a selecting portion for selecting the respective set points of thefunction circuit block from the set point register block or theautomatic set point changing block according to the control data fromthe set point register block.
 8. A semiconductor image pickup deviceaccording to claim 7, wherein each automatic set point changing blockcomprises an increment function register for producing the set points byincrementing a set point by a prescribed value in the image pickup timeperiod of the pixel array.
 9. A semiconductor image pickup deviceaccording to claim 7, wherein each automatic set point changing blockcomprises a decrement function register for producing the set points bydecrementing a set point by a prescribed value in the image pickup timeperiod of the pixel array.
 10. A semiconductor image pickup deviceaccording to claim 7, wherein each automatic set point changing blockcomprises a shift function register for producing the set points byrepeatedly doubling or halving a set point in the image pickup timeperiod of the pixel array.
 11. A semiconductor image pickup deviceaccording to claim 7, wherein each automatic set point changing blockcomprises a plurality of set point registers for registering the setpoints so as to be read out in the image pickup time period of the pixelarray.
 12. A semiconductor image pickup device according to claim 7,wherein each automatic set point changing block comprises a memory forstoring the set points so as to be read out in the image pickup timeperiod of the pixel array.
 13. A semiconductor image pickup deviceaccording to claim 7, wherein each automatic set point changing blockcomprises an automatic setting unit which produces the set points whichare optimum to check the corresponding function circuit block.